1. Field of the Invention:
This invention relates generally to drain cocks or valves and more particularly, it relates to an improved oil drain valve assembly which is used for draining oil from an engine crankcase of a small internal combustion engine such as those encountered on lawn and garden tractors, riding lawn mowers, snow blowers, and the like.
2. Description of the Prior Art:
As is generally known, in order to change the crankcase oil in small internal combustion engines there is typically required the procedure of unscrewing a threaded male plug received within the threaded crankcase opening, drainage of the crankcase oil therefrom, and screwing in the plug prior to refilling of the crankcase with new, clean oil. This operation, especially when practiced by the home consumer, is usually quite messy and inconvenient since it results in the oil leaking everywhere, such as all over the mower deck and subsequently the driveway.
There have been numerous attempts made in the prior art to eliminate this undesirable situation by designing drain plug assemblies which allow drainage in a more simple manner. However, these prior art drain plug assemblies have been found to be unsatisfactory since they usually are completely made of a metal material which may become quite hot at certain times and also require the use of a hand tool (wrench, pliers, etc.). In addition, these metal type drain plug assemblies of the prior art may sometimes by over-tightened into the crankcase, thereby causing physical damage thereto.
It would therefore be desirable to provide an improved oil drain valve assembly which is simple in design and operation for draining engine oil from a small combustion engine without requiring the use of hand tools. Further, it would be expedient that the oil drain valve assembly be operable by an unskilled person and which is not inconvenient and messy to use so as to avoid causing oil leaks and spills.
A prior art search directed to the subject matter of this application in the U.S. Patent and Trademark Office revealed the following U.S. Letters Patent:
______________________________________ 63,680 1,678,927 3,948,481 476,957 1,857,940 4,177,949 1,210,707 2,987,080 4,314,689 1,442,226 3,727,638 4,445,530 1,555,013 3,880,401 4,807,847 1,611,611 ______________________________________
In U.S. Pat. No. 1,678,927 to A. J. Weatherhead, Jr. issued on July 31, 1928, there is disclosed a drain cock which is comprised of a valve member and a tubular body. The tubular body includes a screw-threaded opening and a valve seat. The valve member has a screw-threaded portion adapted to operate with the screw-threaded opening and an inner closed end engageable with the valve seat. A pair of openings is formed in the opposite sides of the valve member so as to communicate with a longitudinal bore therein to permit escape of the fluid when the valve is unseated. A handle is affixed to the opened outer end of the valve member which can be rotated so as to effect longitudinal movement of the valve member within the tubular body, thereby opening and closing the fluid passage.
In U.S. Pat. No. 3,727,638 to John P. Zaremba, Jr., et al. issued on Apr. 17, 1973, there is disclosed a liquid reservoir drain plug assembly comprised of a first tubular female plug member and a second tubular male member. The first member has a tapered top portion and is adapted to be received by a drain outlet in the reservoir. The second member is adapted to be tightly received by the first member in the tapered portion thereof. The second member has a top portion and a bottom portion, with the top portion terminating in a cone and having openings in its sides. When the second member is loosened, liquid is allowed to flow from the reservoir through the tapered portion of the first member and through the second member via the openings in its top portion.
U.S. Pat. No. 3,948,481 to Barry R. Pollock issued on Apr. 6, 1976, teaches a draincock for an automotive cooling system which includes a tubular integral body having external threads at a forward end and a through bore having internal threads at a rear end, and a valve stem having external threads in engagement with the internal body threads. The body has a radial end face which intercepts a counterbore so as to form an annular seat. A valve stem is provided with an integral handle at a rearward end and an integral head at a forward end. The stem has an axial passage extending from the head to a rearward face of the handle. The stem also has a port on its periphery communicating with the axial passage to conduct fluid from a zone surrounding the head through the stem. The stem is further provided with a conical sealing surface which is adapted to sealingly engage the annular seat.
U.S. Pat. No. 4,807,847 to Mitchell R. Martz issued on Feb. 28, 1989, teaches a valved oil pan plug for draining oil from vehicle oil pans which includes a body having a threaded stem for permanently attaching the body to the pan threaded drain hole and a valve threadedly received within the body. The valve includes a conical seat surface seating against a conical valve seat within the body bore. The valve includes an axial bore having inlet ports receiving the pan oil upon the valve seat disengaging from the body seat. This is accomplished by rotating the valve so as to unloosen and retract the same within the body bore which separates the seat surface from the valve seat.
The remaining patents, listed above but not specifically discussed, are deemed to be of only general interest and are cited to show the state of the art in drain plug assemblies.
Further, there is shown in FIG. 15 a prior art oil drain valve which is also known to the applicants of the present invention. The oil drain valve is comprised of a valve body member 2, collar 4, valve core 6, and seal 8. The valve core 6 includes an integral hose barb 3 at a remote end thereof for ease of attachment to a hose for draining. The valve core 6, which is non-rotatable, extends through the collar 4 captivating one end of the valve body member 2. The interior end of the valve core 6 is joined to the seal 8 with the valve body member 2. Movement of the collar 4 by rotation will cause sliding of the valve core 6 relative to the valve body member 2, thereby permitting the seal 8 to open and close the drain outlet 5.
None of the prior art discussed above disclosed an oil drain valve assembly like that of the present invention which includes an adaptor threaded into a crankcase opening, an outer sleeve assembly having a valve subassembly disposed therein and being adapted to telescopingly receive the lower end of the adaptor, and interlocking means formed on the upper end of the outer sleeve assembly and on the exterior surface of the adaptor for permitting opening of the valve assembly. This is accomplished by a relatively limited counterclockwise rotation and subsequent pulling of the outer sleeve assembly relative to the adaptor.